Dual Antiplatelet Therapy Prior to Carotid Endarterectomy Reduces Post-operative Embolisation and Thromboembolic Events: Post-operative Transcranial Doppler Monitoring is now Unnecessary

Perioperative platelet reactivity over time in patients undergoing vascular surgery: An observational pilot study

BACKGROUND

Despite Antiplatelet therapy (APT), cardiovascular patients undergoing revascularisation remain at high risk for thrombotic events. Individual response to APT varies substantially, resulting in insufficient protection from thrombotic events due to high on-treatment platelet reactivity (HTPR) in ≤40% of patients. Individual variation in platelet response impairs APT guidance on a single patient level. Unfortunately, little is known about individual platelet response to APT over time, timing for accurate residual platelet reactivity measurement, or the optimal test to monitor residual platelet reactivity.

AIMS

To investigate residual platelet reactivity variability over time in individual patients undergoing carotid endarterectomy (CEA) treated with clopidogrel.

METHODS

Platelet reactivity was determined in patients undergoing CEA in a prospective, single-centre, observational study using the VerifyNow (change in turbidity from ADP-induced binding to fibrinogen-coated beads), the VASP assay (quantification of phosphorylation of vasodilator-stimulated phosphoprotein), and a flow-cytometry-based assay (PACT) at four perioperative time points. Genotyping identified slow (CYP2C19*2 and CYP2C19*3) and fast (CYP2C19*17) metabolisers.

RESULTS

Between December 2017 and November 2019, 50 patients undergoing CEA were included. Platelet reactivity measured with the VerifyNow (p = < .001) and VASP (p = .029) changed over time, while the PACT did not. The VerifyNow identified patients changing HTRP status after surgery. The VASP identified patients changing HTPR status after eight weeks (p = .018). CYP2C19 genotyping identified 13 slow metabolisers.

CONCLUSION

In patients undergoing CEA, perioperative platelet reactivity measurements fluctuate over time with little agreement between platelet reactivity assays. Consequently, HTPR status of individual patients measured with the VerifyNow and VASP assay changed over time. Therefore, generally used perioperative platelet reactivity measurements seem unreliable for adjusting perioperative APT strategy.

Short-term outcomes after selective shunt during carotid endarterectomy: a propensity score matching analysis

INTRODUCTION AND OBJECTIVES

Carotid cross-clamping during carotid endarterectomy might lead to intraoperative neurologic deficits, increasing stroke/death risk. If deficits are detected, carotid shunting has been recommended to reduce the risk of stroke. However, shunting may sustain a specific chance of embolic events and subsequently incurring harm. Current evidence is still questionable regarding its clear benefit. The aim is to determine whether a policy of selective shunt impacts the complication rate following an endarterectomy.

MATERIAL AND METHODS

From January 2013 to May 2021, all patients undergoing carotid endarterectomy under regional anesthesia with intraoperative neurologic alteration were retrieved. Patients submitted to selective shunt were compared to a non-shunt group. A 1:1 propensity score matching (PSM) was performed. Differences between the groups and clinical outcomes were calculated, resorting to univariate analysis.

RESULTS

Ninety-eight patients were selected, from which 23 were operated on using a shunt. After PSM, 22 non-shunt patients were compared to 22 matched shunted patients. Concerning demographics and comorbidities, both groups were comparable to pre and post-PSM, except for chronic heart failure, which was more prevalent in shunted patients (26.1%, P=0.036) in pre-PSM analysis. Regarding 30-day stroke and score Clavien-Dindo ≥2, no significant association was found (P=0.730, P=0.635 and P=0.942, P=0.472, correspondingly, for pre and post-PSM).

CONCLUSIONS

In this cohort, resorting to shunting did not demonstrate an advantage regarding 30-day stroke or a Clavien-Dindo ≥ 2 rates. Nevertheless, additional more extensive studies are mandatory to achieve precise results concerning the accurate utility of carotid shunting in this subset of patients under regional anesthesia.

One month follow-up of carotid endarterectomy with in-hospital preoperative aspirin monotherapy and postoperative dual antiplatelet therapy in asymptomatic and symptomatic patients: A multi-center study

Background

There is currently no consensus regarding the optimal perioperative antiplatelet strategy for carotid artery surgery. This multicentre study aimed to analyse the association between preoperative aspirin monotherapy following postoperative dual antiplatelet therapy (DAPT) and the risk for stroke and death after carotid endarterectomy (CEA).

Methods

This cohort study included 821 patients with carotid artery stenosis who underwent CEA. Primary outcomes included any stroke or death up to the one-month postoperative follow-up. Multilevel multivariate regression analyses and descriptive statistics were performed.

Results

Patients were predominantly male (53 %), with a mean age of 66.2 years. The primary outcome occurred in 1.6 % of patients. Univariate and multivariate analyses revealed that patients with chronic obstructive pulmonary disease (COPD) exhibited a high risk for stroke or death (P = 0.011). The occurrence of any local complications in the neck was accompanied by an increase in diastolic blood pressure (DBP) (P = 0.007). Patients with a high systolic blood pressure (SBP) (P = 0.002) experienced a longer operative duration. The length of hospital stay was longer in the patients with COPD (P = 0.020), minor stroke (P = 0.011), and major stroke (P = 0.001). A positive linear correlation was found between SBP and operative duration in the overall population (β 0.4 [95 % confidence interval (CI) 0.1-0.7]; P = 0.002). The resultant curve for DBP and any local complications in the neck exhibited a two-stage change and one breakpoint in the entire population (k = 68 mmHg, <68; odds ratio [OR] 0.9 [95 % CI 0.7-1.1], P = 0.461; ≥68: OR 1.1 [95 % CI 1.0-1.1], P = 0.003).

Conclusions

Preoperative aspirin monotherapy and postoperative DAPT were safe and effective antiplatelet treatments for patients who underwent CEA.

Peri-Operative Outcomes of Carotid Endarterectomy are Not Improved on Dual Antiplatelet Therapy vs. Aspirin Monotherapy: A Systematic Review and Meta-Analysis

OBJECTIVE

A systematic review and meta-analysis of the peri-operative outcomes of carotid endarterectomy (CEA) on dual antiplatelet therapy (DAPT) vs. aspirin monotherapy was carried out, to determine optimal peri-operative management with these antiplatelet agents.

DATA SOURCES

The Web of Science, Pubmed, and Embase databases were searched from inception to July 2021. The corresponding authors of excluded articles were contacted to obtain additional data for possible inclusion.

REVIEW METHODS

The main outcomes included ischaemic complications (stroke, transient ischaemic attack [TIA], and transcranial Doppler [TCD] measured micro-emboli), haemorrhagic complications (haemorrhagic stroke, neck haematoma, and re-operation for bleeding), and composite outcomes. Pooled estimates using odds ratios (ORs) were combined using a random or fixed effects model based on the results of the chi square test and calculation of I².

RESULTS

In total, 47 411 patients were included in 11 studies, with 14 345 (30.2%) receiving DAPT and 33 066 (69.7%) receiving aspirin only. There was no significant difference in the rates of peri-operative stroke (OR 0.87, 95% confidence interval [CI] 0.72 - 1.05) and TIA (OR 0.78, 95% CI 0.52 - 1.17) despite a significant reduction in TCD measured micro-emboli (OR 0.19, 95% CI 0.10 - 0.35) in the DAPT compared with the aspirin monotherapy group. Subgroup analysis did not reveal any significant difference in ischaemic stroke risk between patients with asymptomatic and symptomatic carotid artery stenosis. DAPT was associated with an increased risk of neck haematoma (OR 2.79, 95% CI 1.87 - 4.18) and re-operation for bleeding (OR 1.98, 95% CI 1.77 - 2.23) vs. aspirin. Haemorrhagic stroke was an under reported outcome in the literature.

CONCLUSION

This meta-analysis found that CEA while on DAPT increased the risk of haemorrhagic complications, with similar rates of ischaemic complications, vs. aspirin monotherapy. This suggests that the risks of performing CEA on DAPT outweigh the benefits, even in patients with symptomatic carotid stenosis. The overall quality of studies was low, and improved reporting of CEA outcomes in the literature is necessary.

Platelet function assessed by ROTEM® platelet in patients receiving antiplatelet therapy during cardiac and vascular surgery

Patients undergoing coronary artery bypass graft (CABG) surgery or carotid endarterectomy (CEA) continue antiplatelet therapy perioperatively, which may increase bleeding risk. We aimed to investigate whether Rotational thromboelastometry (ROTEM^®) platelet, a newly marketed platelet function analysis, would detect antiplatelet therapy in CABG and CEA patients; whether detection of reduced platelet function was associated with increased bleeding; and whether ex vivo desmopressin increased platelet function. We included 20 CABG patients continuing aspirin and 20 CEA patients continuing clopidogrel (n = 1) or clopidogrel and aspirin (n = 19). Platelet function was analyzed with ROTEM^® platelet and light transmission aggregometry (LTA). According to the lower reference limit, ROTEM^® platelet managed to detect aspirin, but clopidogrel detection was inadequate compared to LTA. Using a previously published cut-off for bleeding risk, 6 (30%) patients receiving aspirin and 4 (21%) patients receiving both clopidogrel and aspirin demonstrated platelet function below this cut-off. One of the four CEA patients below the cut-off died from intracerebral hemorrhage postoperatively. CABG patients below (n = 6) and above (n = 14) the cut-off did not differ in chest tube output (median [range]: 373 ml [250-900] vs. 368 ml [195-820]). Ex vivo addition of desmopressin did not increase platelet function. In conclusion, ROTEM^® platelet does reveal aspirin treatment whereas clopidogrel treatment is most often overlooked. Due to low bleeding in the study population, it was not possible to conclude on the association with bleeding risk.

Impact of intraoperative neurologic deficits in carotid endarterectomy under regional anesthesia

OBJECTIVE

Patients undergoing carotid endarterectomy (CEA) may experiment neurologic deficits during the carotid cross-clamping due to secondary cerebral hypoperfusion. An associated risk of postoperative stroke incidence is also well established. This work aimed to assess the postoperative adverse events related to neurologic deficits in the awake test after clamping and to determine its predictive factors. Methods. From January 2012 to January 2018, 79 patients from a referral hospital that underwent CEA with regional anesthesia for carotid stenosis and manifested neurologic deficits were gathered. Consecutively selected controls (n = 85) were submitted to the same procedure without developing neurological changes. Postoperative complications such as stroke, myocardial infarction, all-cause death, and Clavien-Dindo classification were assessed 30 days after the procedure. Univariate and binary logistic regressions were performed for data assessment. Results. Patients with clamping associated neurologic deficits were significantly more obese than the control group (aOR = 9.30; 95% CI: 2.57-33.69; p = .01). Lower degree of ipsilateral stenosis and higher degree of contralateral stenosis were independently related to clamping intolerance (aOR = 0.70; 95% CI: 0.49-0.99; p = .047 and aOR = 1.30; 95% CI: 1.06-1.50; p = .009, respectively). Neurologic deficits were a main 30-day stroke predictor (aOR = 4.30; 95% CI: 1.10-16.71; p = .035). Conclusions. Neurologic deficits during carotid clamping are a predictor of perioperative stroke. Body mass index > 30 kg/m², a lower degree of ipsilateral stenosis, and a higher degree of contralateral stenosis are independent predictors of neurologic deficits and, therefore, might play a role in the prevention of procedure-related stroke.

Efficacy of near-infrared spectroscopy cerebral oximetry on detection of critical cerebral perfusion during carotid endarterectomy under regional anesthesia

Summary: Background: Patients undergoing carotid endarterectomy (CEA) may suffer from cerebral hypoperfusion during the carotid cross-clamping. Near-infrared spectroscopy cerebral oximetry (NIRS) is a non-invasive method of regional cerebral oxygen saturation measurement reflecting changes in cerebral blood flow during CEA. The main goal of the study was to evaluate the accuracy of the NIRS in detecting cerebral hypoperfusion during CEA under regional anesthesia (RA) and compare it with awake neurological testing. Patients and methods: A prospective observational study of 28 patients that underwent CEA in RA and manifested neurologic deficits, and 28 consecutive controls from a tertiary and referral center, was performed. All patients were monitored with NIRS cerebral oximetry and awake testing as the control technique. Subsequently, operating characteristic curve and Cohen’s kappa coefficient were determined to evaluate the reliability of the monitoring test. Results: NIRS presented a sensitivity of 27.3% and a specificity of 89.3% in comparison to awake testing. Receiver operating characteristic (ROC) curve analysis demonstrated that a decrease of at least 20% in cerebral oxygen saturation is the best threshold to infer cerebral hypoperfusion. However, the respective area under the curve (AUROC) was 0.606 (95% CI: 0.456–0.756, P = 0.178) with a calculated Cohen’s kappa of 0.179, P = 0.093. Regarding 30-days outcomes, only awake testing has shown significant associations with stroke and postoperative complications ( P = 0.043 and P = 0.05), which were higher in patients with post-clamping neurologic deficits. Conclusions: NIRS demonstrated a reduced discriminative capacity for critical cerebral hypoperfusion, and does not seem to add substantial clinical benefits to the awake test.

Benefit of selective shunt use during carotid endarterectomy under regional anesthesia

Objectives

Carotid cross-clamping during endarterectomy exposes the patient to intraoperative neurological deficits due to embolism or cerebral hypoperfusion. To prevent further cerebrovascular incidents, resorting to shunt is frequently recommended. However, since this method is also considered a stroke risk factor, the use is still controversial. This study aims to shed some light on the best approach regarding the use of shunt in symptomatic cerebral malperfusion after carotid artery cross-clamping.

Methods

From January 2012 to January 2018, 79 patients from a tertiary referral hospital who underwent carotid endarterectomy with regional anesthesia for carotid artery stenosis and manifested post-clamping neurologic deficits were prospectively gathered. Shunt use was left to the decision of the surgeon and performed in 31.6% (25) of the patients. Demographics, comorbidities, imaging tests, and clinical/intraoperative features were evaluated. For data assessment, univariate analysis was performed.

Results

Regarding 30-day stroke, 30-day postoperative complications (stroke, surgical hematoma, hyperperfusion syndrome), and cranial nerve injury, no significant differences were found ( P = 0.301, P = 0.460, and P = 0.301, respectively) between resource to shunt and non-shunt. Clamping and surgery times were significantly higher in the shunt group ( P < 0.001 and P = 0.0001, respectively).

Conclusions

Selective-shunting did not demonstrate superiority for patients who developed focal deficits regarding stroke or other postoperative complications. However, due to the limitations of this study, the benefit of shunting cannot be excluded. Further randomized trials are recommended for precise results on this matter with current sparse clinical evidence.

Dual versus Single Antiplatelet Therapy in Carotid Artery Endarterectomy: Direct Comparison of Complications Related to Antiplatelet Therapy

BACKGROUND

Dual and single antiplatelet therapies are routinely used in carotid artery endarterectomy (CEA). However, the efficacy and safety of these therapies are controversial. The present study aimed to comprehensively compare the clinical outcomes between dual and single antiplatelet therapies in CEA.

METHODS

This study retrieved available academic studies evaluating the complications related to antiplatelet therapy between dual and single antiplatelet therapies in CEA from the databases of ScienceDirect, the Cochrane Library, EMBASE, and PubMed. References to previous reviews and related clinical trials were manually checked to retrieve potential literature that was not included in our electronic search results.

RESULTS

A total of 10 articles (1 randomized controlled trial, 9 non-randomized controlled trials) were included in the study. The overall number of patients in the dual antiplatelet group was 14,280, and the number of patients in the single antiplatelet group was 125,850. The results revealed that the single antiplatelet group had a lower incidence of 30-day death (rate difference [RD] 0.002; 95% confidence interval [CI] 0.000-0.003; P = 0.014), neck hematoma (odds ratio [OR] 2.120; 95% CI 1.431-3.142; P < 0.001), myocardial infarction (RD 0.004; 95% CI 0.001-0.007; P = 0.003), and major bleeding (RD 0.005; 95% CI 0.002-0.008; P < 0.001). Meanwhile, the single antiplatelet group was associated with a shorter operation time (weighted mean difference 4.000; 95% CI= 2.564-5.436; P < 0.001). However, there was no significant difference in the rate of postoperative transient ischemic attack (P = 0.215), stroke (P = 0.130), or length of stay (P = 0.563).

CONCLUSIONS

Based on current evidence, using single antiplatelet therapy in CEA may reduce operation time and the incidences of 30-day death, neck hematoma, major bleeding, and myocardial infarction without increasing the risks of transient ischemic attack, stroke, or a longer operation time.

Registry report on prediction by Pocock cardiovascular score of cerebral microemboli acutely following carotid endarterectomy

Background

Cerebral microemboli may lead to ischaemic neurological complications after carotid endarterectomy (CEA). The association between classical cardiovascular risk factors and acute cerebral microemboli following carotid surgery has not been studied. The aim of this study was to explore whether an established cardiovascular risk score (Pocock score) predicts the presence of cerebral microemboli acutely after CEA.

Subjects and methods

Pocock scores were assessed for the 670 patients from the Carotid Surgery Registry (age 71±1 (SEM) years, 474 (71%) male, 652 (97%) Caucasian) managed from January 2002 to December 2012 in the Regional Vascular Centre at University Hospitals Coventry and Warwickshire NHS Trust, which serves a population of 950 000. CEA was undertaken in 474 (71%) patients for symptomatic carotid stenosis and in 196 (25%) asymptomatic patients during the same period. 74% of patients were hypertensive, 71% were smokers and 49% had hypercholesterolaemia.

Results

A high Pocock score (≥2.3%) was significantly associated with evidence of cerebral microemboli acutely following CEA (P=0.039, Mann-Whitney (MW) test). A Pocock score (≥2.3%) did not predict patients who required additional antiplatelet therapy (microemboli signal (MES) rate >50 hour^-1: P=0.164, MW test). Receiver operating characteristic analysis also showed that the Pocock score predicts acute postoperative microemboli (area under the curve (AUC) 0.546, 95% CI 0.502 to 0.590, P=0.039) but not a high rate of postoperative microemboli (MES >50 hour⁻¹: AUC 0.546, 95% CI 0.482 to 0.610, P=0.164). A Pocock score ≥2.3% showed a sensitivity of 74% for the presence of acute postoperative cerebral microemboli. A Pocock score ≥2.3% also showed a sensitivity of 77% and a negative predictive value of 90% for patients who developed a high microembolic rate >50 hour⁻¹ after carotid surgery.

Conclusion

These findings demonstrate that the Pocock score could be used as a clinical tool to identify patients at high risk of developing acute postoperative microemboli.

Cranial nerve injury is associated with dual antiplatelet therapy use and cervical hematoma after carotid endarterectomy

OBJECTIVE

To determine predictors of cranial nerve injury (CNI) after carotid endarterectomy (CEA).

METHODS

Consecutive CEAs performed over a 5-year period were enrolled in this study. Outcomes analyzed included 30-day major adverse event rate (composite of stroke, death, and myocardial infarction), death, stroke, disabling stroke, myocardial infarction, cervical hematoma and CNI rate, reoperation, and hospital readmission at 30 days.

RESULTS

There were 1258 CEAs were included in the study, 1168 (93%) were performed using an eversion technique. Patients with symptoms comprised 27% of the cohort (n = 340). At 30 days, there were no deaths, 23 major adverse events (1.8%), 11 strokes (0.9%: nine minor, two major), 12 myocardial infarctions (0.9%), 41 cervical hematomas (3.3%), 9 reoperations (0.7%) and 10 hospital readmissions (0.8%). Median duration of stay was 1 day (interquartile range, 1-2 days). CNI rate at discharge was 2.3% (n = 29). Two patients (9%) had more than one cranial nerve affected. The marginal mandibular branch of the facial nerve was most frequently involved (n = 16; 52%), followed by the hypoglossal (n = 9; 29%), the vagus (n = 4; 13%), and the spinal accessory nerve (n = 2; 6%). Horner's syndrome, consistent with an injury to the cervical sympathetic chain, occurred in 13 patients (1%) who had a true cranial nerve affected as well. The vast majority (94%) of these CNIs and all Horner's syndrome neurapraxias were transient; only the two accessory lesions persisted at their follow-up visit (median, 32 months; range, 8-72 months). Significant predictors for CNI included diabetes (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.0-6.2; P = .048), cervical hematoma (OR, 41.7; 95% CI, 13.8-125.4; P < .001), and dual antiplatelet therapy (OR, 4.4; 95% CI, 1.7-11.4; P = .002).

CONCLUSIONS

CNI is predominantly a transient complication, but is associated significantly with dual antiplatelet therapy use and the occurrence of a postoperative cervical hematoma. Scrupulous attention to hemostasis might reduce the incidence of CNI.

Effects of Sarpogrelate Combined with Aspirin in Patients Undergoing Carotid Endarterectomy in China: A Single-Center Retrospective Study

BACKGROUND

Patients undergoing carotid artery stenosis who are prescribed aspirin, clopidogrel, or sarpogrelate as treatment options to inhibit platelet aggregation continues to increase. The purpose of this study was to compare the efficacy and safety of clopidogrel combined with aspirin (CA) versus sarpogrelate combined with aspirin (SA) treatment in carotid endarterectomy (CEA) patients.

METHODS

This retrospective study included 197 CEA patients (mean age 61.4 years, mean follow-up time 42.5 months), who were divided into a CA group (Group A: 65 male and 44 female patients) and an SA group (Group B: 58 male and 30 female patients). Preoperative demographic and clinical characteristics and postoperative results were compared between the 2 groups and statistically analyzed.

RESULTS

Preoperative demographic and clinical characteristics, transfusions, hospital stay, occurrence of transient ischemic attack, stroke, myocardial infarction, restenosis, general or life-threatening bleeding, and 30-day mortality showed no significant differences between the 2 CEA patient groups. However, the mean operative blood loss (P = 0.023) and the operative time (P = 0.040) were significantly higher in Group A compared with Group B. A highly significant incidence of neck hematoma (P = 0.024) was observed in patients of Group A.

CONCLUSIONS

In this study on CEA patients, antiplatelet treatment with CA resulted in a significant risk of developing neck hematoma, increased operative blood loss, and operative time compared with SA treatment. Long-term prospective studies with larger study populations are needed to further confirm the utility of SA treatment for CEA patients.

Dual antiplatelet therapy reduces stroke but increases bleeding at the time of carotid endarterectomy

OBJECTIVE

Controversy persists regarding the perioperative management of clopidogrel among patients undergoing carotid endarterectomy (CEA). This study examined the effect of preoperative dual antiplatelet therapy (aspirin and clopidogrel) on in-hospital CEA outcomes.

METHODS

Patients undergoing CEA in the Vascular Quality Initiative were analyzed (2003-2014). Patients on clopidogrel and aspirin (dual therapy) were compared with patients taking aspirin alone preoperatively. Study outcomes included reoperation for bleeding and thrombotic complications defined as transient ischemic attack (TIA), stroke, or myocardial infarction. Secondary outcomes were in-hospital death and composite stroke/death. Univariate and multivariable analyses assessed differences in demographics and operative factors. Propensity score-matched cohorts were derived to control for subgroup heterogeneity.

RESULTS

Of 28,683 CEAs, 21,624 patients (75%) were on aspirin and 7059 (25%) were on dual therapy. Patients on dual therapy were more likely to have multiple comorbidities, including coronary artery disease (P < .001), congestive heart failure (P < .001), and diabetes (P < .001). Patients on dual therapy were also more likely to have a drain placed (P < .001) and receive protamine during CEA (P < .001). Multivariable analysis showed that dual therapy was independently associated with increased reoperation for bleeding (odds ratio [OR], 1.71; 95% confidence interval [CI], 1.20-2.42; P = .003) but was protective against TIA or stroke (OR, 0.61; 95% CI, 0.43-0.87; P = .007), stroke (OR, 0.63; 95% CI, 0.41-0.97; P = .03), and stroke/death (OR, 0.66; 95% CI, 0.44-0.98; P = .04). Propensity score matching yielded two groups of 4548 patients and showed that patients on dual therapy were more likely to require reoperation for bleeding (1.3% vs 0.7%; P = .004) but less likely to suffer TIA or stroke (0.9% vs 1.6%; P = .002), stroke (0.6% vs 1.0%; P = .04), or stroke/death (0.7% vs 1.2%; P = .03). Within the propensity score-matched groups, patients on dual therapy had increased rates of reoperation for bleeding regardless of carotid symptom status. However, asymptomatic patients on dual therapy demonstrated reduced rates of TIA or stroke (0.6% vs 1.5%; P < .001), stroke (0.4% vs 0.9%; P = .01), and composite stroke/death (0.5% vs 1.0%; P = .02). Among propensity score-matched patients with symptomatic carotid disease, these differences were not statistically significant.

CONCLUSIONS

Preoperative dual antiplatelet therapy was associated with a 40% risk reduction for neurologic events but also incurred a significant increased risk of reoperation for bleeding after CEA. Given its observed overall neurologic protective effect, continued dual antiplatelet therapy throughout the perioperative period is justified. Initiating dual therapy in all patients undergoing CEA may lead to decreased neurologic complication rates.

[Anti-platelets without a bleeding risk: novel targets and strategies]

Anti-platelet agents such as aspirin, clopidogrel and antagonists of integrin αIIbβ3 allowed to efficiently reduce morbidity and mortality associated with arterial thrombosis. A major limit of these drugs is that they increase the risk of bleeding. During the last few years, several innovative anti-thrombotic strategies with a potentially low bleeding risk were proposed. These approaches target the collagen receptor glycoprotein (GP) VI, the GPIb/von Willebrand factor axis, the thrombin receptor PAR-1, the activated form of integrin αIIbβ3 or the ADP receptor P2Y1. While an antagonist of PAR-1 was recently marketed, the clinical proofs of the efficiency and safety of the other agents remain to be established. This review evaluates these new anti-platelet approaches toward safer anti-thrombotic therapies.

Intraoperative Changes in Cerebrospinal Fluid Gas Tensions Reflect Paraplegia During Thoracoabdominal Aortic Surgery

Background:

In this study, gas tensions in cerebrospinal fluid (CSF) were prospectively evaluated as intraoperative markers for the detection of neurological deficits.

Methods:

Spinal fluid, serum, and heart lung machine (HLM) perfusate were monitored for gas tensions (po2/pCo2) and related parameters (pH, lactate, and glucose) during thoracoabdominal aortic repair and correlated with perioperative neurological examination and electrophysiological testing.

Results:

Forty-seven patients were assessed for the study, and 40 consecutive patients were finally included. The patients were divided into 3 groups: group A (23 patients, 57.5%): no clinical or laboratory signs of neurological damage; group B (14 patients, 35%) who developed subclinical deficits; and group C (3 patients, 7.5%) who had paraplegia. Significant intraoperative changes in CSF gas tensions were observed with postoperative paraplegia. Glucose ratio between serum and CSF showed higher variability in group C, confirming a damage of the blood–brain barrier (BBB).

Conclusion:

Major neurological damage is reflected by early changes in CSF gas tensions and glucose variability, suggesting damage of the BBB in these patients.

Ascertainment of any and all neurologic and myocardial damage in carotid revascularization: the key to optimization?

The majority of carotid revascularization procedures performed at present are in asymptomatic patients. Since such procedures convey no immediate benefit, but rather protect from future hazard, optimization of procedural safety is mandatory. The authors focus their discussion on the methodologies that assess periprocedural myocardial damage and brain injury, as used in past clinical trials, from the fields of perioperative medicine and neurovascular imaging, and discuss methodologies to reduce both events in carotid revascularization.

Changes in middle cerebral artery velocity after carotid endarterectomy do not identify patients at high-risk of suffering intracranial haemorrhage or stroke due to hyperperfusion syndrome

OBJECTIVES

To determine if significant increases in middle cerebral artery velocity (MCAV) or pulsatility index (PI) during and immediately after carotid endarterectomy (CEA) were predictive of patients suffering a stroke due to the hyperperfusion syndrome (HS) or intracerebral haemorrhage (ICH).

METHODS

Transcranial Doppler (TCD) mean/peak MCAV and PI were recorded pre-operatively; pre-clamp; 1-min post-declamping; 10-min post-declamping and 30-min post-operatively. The study was divided into two time periods; Group 1 (1995-2007); where there was no formal guidance for managing post-CEA hypertension (PEH) and Group 2 (2008-2012); where written guidelines for treating PEH were available.

RESULTS

11/1024 patients in Group 1 (1.1%) suffered a stroke due to HS/ICH, compared to 0/426 patients (0.0%) in Group 2 (p = 0.02). In Group 1; intra-operative increases >100% in mean/peak MCAV and PI at 1 and 10-min post-clamp release had positive predictive values (PPV) of 1.2%, 6.3% and 20.0% and 2.9%, 8.0% and 16.6% respectively. Post-operatively; a >100% increase in mean and peak MCAV had a PPV of 6.3% and 2.7% respectively.

CONCLUSION

We were unable to demonstrate that significant increases in MCAV and PI were able to predict patients at increased risk of suffering a post-operative stroke due to HS or ICH. The provision of written guidance for managing PEH in Group 2 patients was associated with virtual abolition of ICH/HS.

Transient heparin-induced platelet activation linked to generation of platelet 12-lipoxygenase. Findings from a randomised controlled trial

Previously we demonstrated that heparin administration during carotid endarterectomy (CEA) caused a marked, but transient increase in platelet aggregation to arachidonic acid (AA) and adenosine diphosphate (ADP), despite effective platelet cyclo-oxygenase-1 (COX-1) inhibition with aspirin. Here we investigated the metabolism of AA via platelet 12-lipoxygenase (12-LOX) as a possible mediator of the observed transient aspirin resistance, and compared the effects of unfractionated (UFH) and low-molecular-weight (LMWH) heparin. A total of 43 aspirinated patients undergoing CEA were randomised in the trial to 5,000 IU UFH (n=22) or 2,500 IU LMWH (dalteparin, n=21). Platelet aggregation to AA (4x10⁻³) and ADP (3x10⁻⁶) was determined, and the products of the COX-1 and 12-LOX pathways; thromboxane B₂ (TXB₂) and 12-hydroxyeicosatretraenoic acid (12-HETE) were measured in plasma, and in material released from aggregating platelets.Aggregation to AA increased significantly (~10-fold) following heparinisation (p<0.0001), irrespective of heparin type (p=0.33). Significant, but smaller (~2-fold) increases in aggregation to ADP were also seen, which were significantly lower in the platelets of patients randomised to LMWH (p<0.0001). Plasma levels of TxB2 did not rise following heparinisation (p=0.93), but 12-HETE increased significantly in the patients' plasma, and released from platelets stimulated in vitro withADP, with both heparin types (p<0.0001). The magnitude of aggregation to ADP correlated with 12-HETE generation (p=0.03). Heparin administration during CEA generates AA that is metabolised to 12-HETE via the 12-LOX pathway, possibly explaining the phenomenon of transient heparin-induced platelet activation. LMWH has less effect on aggregation and 12-HETE generation than UFH when the platelets are stimulated with ADP.

Histologically unstable asymptomatic carotid plaques have altered expression of genes involved in chemokine signalling leading to localised plaque inflammation and rupture

BACKGROUND

Many studies have evaluated histological and gene expression profiles in TIA/stroke patients after onset of symptoms, but there is limited understanding as to how these plaque related features interact before symptom onset. In particular, no studies have evaluated differential gene expression in histologically unstable (vs stable plaques) in neurologically asymptomatic patients.

METHODS

Nine asymptomatic patients had their plaques scored blindly by two independent Histopathologists using the AHA plaque scoring system. RNA extracted from the plaques was hybridised onto a whole genome microarray. Analysis was performed using GenomeStudio (v1.0) and the DAVID bioinformatics resource (v6.7).

RESULTS

Three plaques were histologically unstable (Grade 2/3), while six were stable (Grade 0/1). 346 differentially expressed genes (>1.3 fold, P < 0.05) were identified (293 down-regulated and 53 up-regulated) between stable and unstable plaques. Genes related to chemokine and protein signalling (pro-inflammatory/pro-apoptotic) were identified to have high enrichment scores (>1.3) and were significantly up-regulated in unstable (asymptomatic) plaques.

CONCLUSION

The findings confirm the intuitively held belief that changes in chemokine and protein signalling may be associated with acute plaque disruption and precede the onset of symptoms. Once validated, these genes could therefore become targets for innovative medical treatments in the future or could help identify asymptomatic patients with histologically unstable plaques that would benefit from surgical intervention.

Diagnosis of and treatment for symptomatic carotid stenosis: an updated review

Carotid stenoses of ≥50% account for about 15-20% of strokes. Their degree may be moderate (50-69%) or severe (70-99%). Current diagnostic methods include ultrasound, MR- or CT-angiography. Stenosis severity, irregular plaque surface, and presence of microembolic signals detected by transcranial Doppler predict the early recurrence risk, which may be as high as 20%. Initial therapy comprises antiplatelets and statins. Benefit of revascularization is greater in men, in older patients, and in severe stenosis; patients with moderate stenoses may also profit particularly if the plaque has an irregular aspect. An intervention should be performed within <2 weeks. In large randomized studies comparing endarterectomy and stenting, endovascular therapy was associated with a higher risk of periprocedural stroke, yet in some studies, with a lower risk of myocardial infarction and of cranial neuropathy. These trials support endarterectomy as the first choice treatment. Risk factors for each of the two therapies have been indentified: coronary artery disease, neck radiation, contralateral laryngeal nerve palsy for endarterectomy, and, elderly patients (>70 years), arch vessel tortuosity and plaques with low echogenicity on ultrasound for carotid stenting. Lastly, in direct comparisons, a contralateral occlusion increases the risk of periprocedural complications in both types of treatment.

Blood loss and complications following carotid endarterectomy in patients treated with clopidogrel

This study assessed the effect of uninterrupted antiplatelet therapy on perioperative blood loss and complications in patients undergoing carotid endarterectomy. The files of 107 consecutive patients (mean age 69.5 ± 9 years; range 47–88; 78 men) who underwent carotid endarterectomy were reviewed. Twenty-six patients had been treated with clopidogrel (16 of whom were on combined clopidogrel and aspirin treatment) and compared with non-clopidogrel patients. Antiplatelet treatment was continued until the day of surgery without interruption. Perioperative blood loss and complications were studied. The mean hemoglobin decrease was 1.64 ± 1.2 mg/dL and was not significantly affected by clopidogrel. Surgical time was significantly longer among patients treated with clopidogrel (205 ± 52 minutes on combined treatment and 201 ± 68 minutes on clopidogrel alone versus 165 ± 33 minutes, P < 0.0001). Postoperative complications were similar for all groups and included five strokes, five neck hematomas, one nerve injury and one wound infection. In conclusion, patients treated with clopidogrel before carotid endarterectomy can be expected to have prolonged surgical time. Large cohorts are required to determine whether these patients have more complications.

Microembolus detection by transcranial Doppler sonography: review of the literature

Transcranial Doppler can detect microembolic signals which are characterized by unidirectional high intensity increase, short duration, random occurrence, and a “whistling” sound. Microembolic signals have been detected in a number of clinical settings: carotid artery stenosis, aortic arch plaques, atrial fibrillation, myocardial infarction, prosthetic heart valves, patent foramen ovale, valvular stenosis, during invasive procedures (angiography, percutaneous transluminal angioplasty), surgery (carotid, cardiopulmonary bypass, orthopedic), and in certain systemic diseases. Microembolic signals are frequent in large artery disease, less commonly detected in cardioembolic stroke, and infrequent in lacunar stroke. This article provides an overview about the current state of technical and clinical aspects of microembolus detection.